The efficiencies afforded by radio frequency identification (RFID) tags are becoming apparent in many supply chain management applications. Having timely electronic access to information concerning an item's progress through a supply chain is valuable for inventory management, controlling costs, theft prevention, shipping and labor scheduling, and many other aspects of supply chain operations. RFID is already utilized in some warehouse and shipping applications, where typically Ultra High Frequency (UHF) (e.g., 902-928 MHz) tags are used on a per-pallet basis because of their long read range performance. However, lower frequencies (e.g., 125 kHz, 13.56 MHz) are considered by many to be more appropriate for inventory or shelving applications. Lower frequency tags have an advantage over higher frequency tags in that they do not exhibit carrier signal reflection issues observed in tags operating at higher frequencies, but are shorter in range. It is generally accepted in the industry that no single frequency is most appropriate for monitoring all stages of the supply chain (i.e., shipping, inventory, shelving, etc.).
The following U.S. patents, which are incorporated herein by reference in their entireties, provide further details regarding RFID tag technology, and the manner in which such technology is made and used: U.S. Pat. Nos. 6,754,190, 6,246,327; 6,107,920; 6,265,977; 6,094,138; 6,091,332; 6,018,299; and 6,611,199.
Unfortunately, a multi-frequency approach presently means that an item needs to have multiple tags affixed to it, so that it can be successfully accounted for at each stage in the supply chain. The associated costs of not only the tags and readers but also the system operating logistics are impeding industry acceptance of multi-frequency applications, despite their benefits. Therefore, an industry need exists for a single tag that operates over multiple frequencies.